Hierarchy of relaxation times in supramolecular polymer model networks
Hierarchy of relaxation times in supramolecular polymer model networks
复制标题
超分子聚合物模型网络中弛豫时间的层次结构
DOI：
10.1039/d1cp04213k
复制
发表时间：
2022
影响因子：
3.3
通讯作者：
Seiffert, Sebastian
中科院分区：
文献类型：
--
作者：
Koziol, Martha Franziska;Nguyen, Phuong Loan;Gallo, Shannon;Olsen, Bradley D.;Seiffert, Sebastian
超分子聚合物凝胶是一类正在发展中的软材料，具有大量的性质，可以根据需要的应用进行调整。尽管在聚合物合成、可持续性或适应性方面不断取得进展，但对瞬变网络中结构、动力学和扩散过程之间的相互作用缺乏一致的理解。在这项研究中，研究了几个松弛过程的层次性，从单个粘贴解离事件的微观角度出发，直到星形聚合物积木在不同长度尺度上的质心扩散，以及由此产生的宏观力学响应。除此之外，第二个焦点放在凝胶的微观结构上，通过光散射进行分析。将动态光散射(DLS)的反长度尺度转换到实际空间，允许将弛豫时间与由强迫瑞利散射(FRS)获得的驰豫时间相结合。在这些研究中，选择了一个由窄分散的四臂聚乙二醇叔吡啶大分子组成的模型型金属超分子网络，这些大分子通过与锌离子的络合相互连接。组合得到的活化能表明，所有复杂的解离支配的驰豫过程都表现出相似的活化能。
Supramolecular polymer gels are an evolving class of soft materials with a vast number of properties that can be tuned to desired applications. Despite continuous advances concerning polymer synthesis, sustainability or adaptability, a consistent understanding of the interplay between structure, dynamics, and diffusion processes within transient networks is lacking. In this study, the hierarchy of several relaxation processes is investigated, starting from a microscopic perspective of a single sticker dissociation event up to the center-of-mass diffusion of a star-shaped polymer building block on different length scales, as well as the resulting macroscopic mechanical response to applied external stress. In addition to that, a second focus is placed on the gel micro-structure that is analyzed by light scattering. Conversion of the dynamic light scattering (DLS) inverse length scale into real space allows for a combination of relaxation times with those obtained by forced Rayleigh scattering (FRS). For these investigations, a model-type metallo-supramolecular network consisting of narrowly dispersed tetra-arm poly(ethylene glycol)-terpyridine macromolecules that are interconnected via complexation with zinc ions is chosen. Assembling the obtained activation energies reveals that all complex dissociation-governed relaxation processes exhibit similar activation energies.